1. Technical Field
The present invention relates in general to a shielded, pluggable, mounting enclosure for printed circuit cards such as used in a computer.
2. Description of the Related Art
As computer systems have become more prevalent in the workplace and in the home, there has become a need to make computer systems more adaptable and interchangeable to allow the customization of a computer system to a particular user's needs. Also, it has become necessary to enable the user to change functions or to add new functions to the computer system. These functions can be provided through software or hardware. When a new hardware function is added to a computer system, the electronics for implementing this function are often contained in a self-contained, pluggable, electronics package.
The electronics package contains a circuit card mounted with a variety of electronic components that implement the required electronic function. For example, the circuit card may provide a processor, expanded memory, an I/O card, or a video card. This circuit card is enclosed by a metal container and is connected to a connector at the back of the electronics package. An electronics package thus constructed is easily configured in a computer system by inserting the package into a provided slot in a "card cage" and engaging the connector at the back of the electronics package with a mating connector on the backplane of the computer system. The computer system backplane provides an appropriate interface for the electronics package to be integrated within the computer system.
Because an electronics package may be inserted and removed from a computer system a number of times, and further since an unskilled user may be inserting and removing the package, the enclosure structure of the electronics package must be sturdy and sufficiently rigid to protect the enclosed circuit card from damage that might be caused by physical manipulation of the electronics package. In addition, it is desirable for the package to have electromagnetic compatibility (EMC) by shielding the circuit card from electromagnetic radiation that may cause interference with the circuit card.
To overcome these problems, the prior art has provided electronics packages having enclosures formed from sheet metal. These metal packages have the strength and durability necessary to protect the circuit cards enclosed, and can form ground planes that shield the circuit card from electromagnetic interference (EMI), as well as reduce the electromagnetic emissions from the electronics package itself.
While the prior art design has been satisfactory, there is an ever increasing number of features and functions being added to various computer systems, requiring a continuous re-design of the prior art circuit cards. These new circuit card designs will necessitate various widths and sizes of electronic packages. However, this re-designing of the package widths requires re-design of the card cage slots that hold the packages and the mating connectors on the backplane. As an alternative to such re-design, future electronic package designs will require increased electronics density within the existing package sizes in order to adhere to the current restrictions on the form factor of the card cage and the maximum number of connectors available on the backplane.